Polymerization of Cyclic Imino Ethers. X. Kinetics, Chain Transfer, and Repolymerization

Litt, Morton H.; Levy, Avishai; Herz, J.

doi:10.1080/00222337508065890

Cited by 163 publications

(150 citation statements)

References 12 publications

Supporting

Mentioning

135

Contrasting

Unclassified

Order By: Relevance

“…[30,31] The thus-formed intermediate oxazolinium species is attacked by a second monomer, thus causing a ring rearrangement that leads to the cleavage of the C À O bond. In general, chain-transfer or termination reactions are absent under appropriate reaction conditions, and hence the polymerization proceeds in a living manner until all the monomer is consumed or a terminating agent, such as water, is added.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Microwave‐Assisted Polymerization, and Polymer Properties of Fluorinated 2‐Phenyl‐2‐oxazolines: A Systematic Study

Lobert

Thijs

Erdmenger

et al. 2008

Chemistry A European J

View full text Add to dashboard Cite

We present a detailed systematic study of the synthesis and ability of fluorinated 2-phenyl-2-oxazolines to undergo polymerization. The synthesis of these compounds is based on a two-step procedure that gives the desired 2-oxazolines in moderate-to-good yields. All the compounds were fully characterized by IR and NMR ((1)H, (13)C, and (19)F) spectroscopy, mass spectrometry, and elemental analysis. The 2-oxazolines were subsequently used as monomers for living cationic ring-opening polymerization (CROP) with microwave irradiation as the heat source (T=140 degrees C), nitromethane as the solvent, and methyl tosylate as the initiator. The linear first-order kinetic plots of the polymerizations accompanied by a linear increase of the molecular weight with conversion and low polydispersity index (PDI) values (generally below 1.30) indicate a living polymerization mechanism. The resulting polymerization rates reflect a strong sensitivity to the quantity of fluorine substituents in general and the presence or absence of ortho-fluoro substituents of the phenyl ring in particular. All the polymers were isolated and characterized by size-exclusion chromatography and MALDI-TOF mass spectrometry. Finally, a detailed investigation of selected polymer properties was performed by using differential scanning calorimetry, thermogravimetric analysis, and contact-angle measurements, thus resulting in structure-property relationships. Whereas the thermal properties of the polymers are mostly influenced by the presence of ortho-fluoro substituents, the surface properties are mainly determined by the presence of para- and/or meta-fluoro substituents.

show abstract

Section: Introductionmentioning

confidence: 99%

Synthesis, Microwave‐Assisted Polymerization, and Polymer Properties of Fluorinated 2‐Phenyl‐2‐oxazolines: A Systematic Study

Lobert

Thijs

Erdmenger

et al. 2008

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…29 This abstraction results in an inactive olefinic polymer species and a positively charged monomer cation. The positively charged monomer cation may then initiate the growth of a new polymer chain, finally leading to lower overall molecular weights.…”

Section: Notementioning

confidence: 99%

Metallocene‐mediated cationic ring‐opening polymerization of 2‐methyl‐ and 2‐phenyl‐oxazoline

Kourti

Vougioukalakis

Hadjichristidis

et al. 2011

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

The cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline and 2‐phenyl‐2‐oxazoline was efficiently used using bis(η5‐cyclopentadienyl)dimethyl zirconium, Cp2ZrMe2, or bis(η5‐tert‐butyl‐cyclopentadienyl)dimethyl hafnium in combination with either tris(pentafluorophenyl)borate or tetrakis(pentafluorophenyl)borate dimethylanilinum salt as initiation systems. The evolution of polymer yield, molecular weight, and molecular weight distribution with time was examined. In addition, the influence of the initiation system and the monomer on the control of the polymerization was studied. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 000: 000–000, 2011

show abstract

“…(de la Rosa et al, 2014) This is at odds with the usually proposed mechanism of chain transfer, which postulates that branch points will be hydrolysed. (Litt et al, 1975;Warakomski and Thill, 1990) Broad l-PEI500 was synthesised by hydrolysis in 16.5% (v/v) hydrochloric acid (degree of hydrolysis (99.6%), the volatiles removed, re-dissolved in boiling water (ca. 5 mL) and made basic with NaOH.…”

Section: Synthesis and Characterisation Of L-peimentioning

confidence: 99%

Cytotoxicity of polycations: Relationship of molecular weight and the hydrolytic theory of the mechanism of toxicity

Monnery

Wright

Cavill

et al. 2017

International Journal of Pharmaceutics

167

162

View full text Add to dashboard Cite

The mechanism of polycation cytotoxicity and the relationship to polymer molecular weight is poorly understood. To gain an insight into this important phenomenon a range of newly synthesized uniform (near monodisperse) linear polyethylenimines, commercially available poly(L-lysine)s and two commonly used PEI-based transfectants (broad 22 kDa linear and 25 kDa branched) were tested for their cytotoxicity against the A549 human lung carcinoma cell line. Cell membrane damage assays (LDH release) and cell viability assays (MTT) showed a strong relationship to dose and polymer molecular weight, and increasing incubation times revealed that even supposedly "non-toxic" low molecular weight polymers still damage cell membranes. The newly proposed mechanism of cell membrane damage is acid catalysed 3 hydrolysis of lipidic phosphoester bonds, which was supported by observations of the hydrolysis of DOPC liposomes.

show abstract

Polymerization of Cyclic Imino Ethers. X. Kinetics, Chain Transfer, and Repolymerization

Cited by 163 publications

References 12 publications

Synthesis, Microwave‐Assisted Polymerization, and Polymer Properties of Fluorinated 2‐Phenyl‐2‐oxazolines: A Systematic Study

Synthesis, Microwave‐Assisted Polymerization, and Polymer Properties of Fluorinated 2‐Phenyl‐2‐oxazolines: A Systematic Study

Metallocene‐mediated cationic ring‐opening polymerization of 2‐methyl‐ and 2‐phenyl‐oxazoline

Cytotoxicity of polycations: Relationship of molecular weight and the hydrolytic theory of the mechanism of toxicity

Contact Info

Product

Resources

About